Customer Requirements Clearance Requirements for Overhead Joint Utility Construction

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Alannah Newton
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1 Application This standard establishes the clearances that are required on utility pole structures between electrical supply facilities owned and operated by Tacoma Power and communication facilities owned and operated by others. Terms Term Joint Utility Worker Safety Zone Supply Transmission Distribution Secondary Supply Neutral Common Position Definition For the purposes of this standard, any entity (utility, public agency, communications company, or other) other than the electrical supply utility that is attached to the structure. The space on joint-use structures where communication facilities are separated from the supply space by the communication Worker safety zone. This space is below the communication worker safety zone. That space as defined in National Electric Safety Code (NESC) Rule 235C4. This zone generally originates at the lowest point of the supply space. This space is intended to maintain a physical separation between supply and communication facilities. The minimum dimensions of this space shall at no time be violated. The space on joint-use structures where supply facilities are separated from the communication space by the communication worker safety zone. This space is above the communication worker safety zone. Tacoma Power supply voltages of 115 kv or 230 kv. Tacoma Power supply voltages of 7.2 kv to 15 kv. Tacoma Power supply voltages of 600 V or less. Multi-grounded conductor of the Distribution system. Nine feet (9 ft.) below the distribution. Transmission & Distribution Standards Page 1 of 13

2 Figure 1 Illustration of Allocation on Pole Supply Common Position Worker Safety Zone Required Ground Figure 2 Illustration of Worker Safety Zone Power Attachment Worker Safety Zone Per Figures 3,4,5,6, & 7 s Attachment Transmission & Distribution Standards Page 2 of 13

3 Clearance Requirements Clearances to Transmission Clearances from transmission to communication underbuild will be determined by the Tacoma Power Line Engineering Department. This standard does not list any clearances of communication cables to Tacoma Power transmission facilities. Clearances to Distribution, Secondary and Supply Neutral Clearances to distribution, secondary and supply neutral conductors will follow the most current version of the NESC unless otherwise noted. At no time will the minimum NESC clearances be compromised. Minimum clearance values listed for existing attachments do not allow for additional communication facilities to be installed at a later date. New Attachments For new communication attachments to existing structures that wish to be installed above existing communications facilities the minimum clearance values must be present. If this is not the case make ready work is likely to be required. Clearances at Supports The minimum clearances at supports between Tacoma Power electrical supply conductors, equipment, and hardware and communication conductors and hardware attached to the same supports are listed in the figures that follow: If and then refer to Figure 3 distribution/supply neutral conductors are mounted on a crossarm at the same level (either single or double arm construction) distribution/supply neutral conductors are mounted on a crossarm at the same level (either single or double arm construction) the supply neutral is located in the common position on the pole secondary conductor is located in the common position a secondary riser is located on the pole there are no additional Tacoma Power conductors or equipment below the crossarm electrical equipment enclosure is mounted beneath the crossarm with no additional Tacoma Power conductors or equipment beneath it there are no secondary conductors on the pole (The clearance is measured from the tie wire or conductor clamp on the insulator to the top of the communication space) Figure 4 Figure 5 Figure 6 Figure 7 Transmission & Distribution Standards Page 3 of 13

4 Figure 3 Clearance to Distribution/Supply Neutral Conductors on Pole with No Other Equipment or Conductors (e.g kv System or Supply Neutral on arm, etc.) Distribution Conductor Supply Neutral Worker Safety Zone 9 min. s Cable Pole Grounding Conductor Minimum Clearance* 9 feet Clearances are designed so that Tacoma Power manlift equipment can move from the road side of the structure to the field side of the structure. The clearances exceed the NESC minimum clearance of 40 in. Transmission & Distribution Standards Page 4 of 13

5 Figure 4 Clearance to Equipment Distribution/Supply Neutral Conductor Supply Grounded Equipment Case 30 Grounded Case 40 Ungrounded Case Worker Safety Zone Minimum Clearance Grounded Case Ungrounded Case 30 inches Transmission & Distribution Standards Page 5 of 13

6 Figure 5 Clearance to Supply Neutral in the Common Position Supply Optional Secondary Rack Supply Rigid Clevis Supply Neutral 40 Minimum Worker Safety Zone NOTE: s shall install as low as possible on the pole while maintaining clearances Minimum Clearance* The minimum clearance may be reduced to 30 inches on a per structure basis as reviewed and approved by the Tacoma Power Line Section. Transmission & Distribution Standards Page 6 of 13

7 Figure 6 Clearance to Secondary Conductor in the Common Position Rigid Clevis Secondary or Service Supply Conductors Supply Drip Loop 40" Minimum Worker Safety Zone NOTE: s shall install as low as possible on the pole while maintaining clearances Minimum Clearance Transmission & Distribution Standards Page 7 of 13

8 Figure 7 Clearance to Secondary Riser Termination (Top of the Conduit) Supply Top of Secondary Riser 40" Minimum Worker Safety Zone NOTE: Risers shall be installed at the same level or above the neutral Minimum Clearance Transmission & Distribution Standards Page 8 of 13

9 Clearances at Midspan between Supports The minimum clearances at midspan between Tacoma Power electrical supply conductors and communication conductors attached to the same supports are listed in the figures that follow: If and then refer to distribution/supply neutral conductors are mounted on a crossarm at the same level (either single or double arm construction) the supply neutral is located in the common position on the pole secondary conductor is located in the common position there are no additional Tacoma Power conductors or equipment below the crossarm there are no secondary conductors on the pole Figure 8 Figure 9 Figure 10 Figure 8 Midspan Clearance between Distribution Conductors and s Cables Distribution/Supply Neutral Conductor 63" min s Cable Minimum Clearance 63 inches Transmission & Distribution Standards Page 9 of 13

10 Figure 9 Midspan Clearance between Supply Neutral and s Cable Supply Neutral 30" min Upper s Cable Minimum Clearance 30 inches Figure 10 Midspan Clearance between Secondary Conductors and s Cable Supply Neutral Secondary Conductor 30" min Upper s Cable Minimum Clearance 30 inches Transmission & Distribution Standards Page 10 of 13

11 Clearances to Street Lights Clearances to street lights have been modified from the clearances to other electric supply facilities due to the nature of their installation. Clearances for Comm Cables Below Street Lights When communication cables are installed below a street light on a structure, all of the following minimum clearances shall be met (see Figure 11): Between the bottom of and the top of the The minimum clearance is street light communication space. Ungrounded Grounded 4 inches drip loop of street light supply wire communication space. Uncovered drip loop Covered drip loop 12 inches 3 inches Figure 11 Clearances for Street Light Above s Supply Bracket Arm 40" Minimum Worker Safety Zone Uncovered 12" Covered 3" Ungrounded 40" Grounded 4" Transmission & Distribution Standards Page 11 of 13

12 Clearances to Street Lights (continued) Clearances for Comm Cables/ Support arms Above Street Lights When communication cables/support arms are installed above a street light on a structure, all of the following minimum clearances shall be met (see Figures 12 and 13): Between the and the The minimum clearance is top of the street light lowest communication attachment Ungrounded Grounded 4 inches top of the street light bottom of the street light supply wire molding/conduit (where the wire is exposed at the drip loop) top of the street light supply wire molding/conduit (where the wire is exposed) bottom of any communication support arm. lowest communication attachment. highest communication attachment. Ungrounded Grounded 72 inches 24 inches Figure 12 Clearances for Street Light Below Cable Supply 40" Worker Safety Zone Protective Molding/Conduit s Cables Ungrounded 40" Grounded 4" 72 To Exposed Wires Transmission & Distribution Standards Page 12 of 13

13 Clearances to Street Lights (continued) Figure 13 Clearances for Street Light Below s Support Arm Supply 40" Worker Safety Zone Protective Molding/Conduit Ungrounded 40" Grounded 24" 72 To Exposed Wires Transmission & Distribution Standards Page 13 of 13

Appalachian Power Company Policy No. 2 Cover Up Procedures. Policy Summary:

Appalachian Power Company Policy No. 2 Cover Up Procedures Policy Summary: A. When a worker is in a position where the worker or a conductive object in the worker s hand can go or reach within the minimum